This page provides information on various analyses conducted by Chicora (or by others who might be willing to have the information listed or a link indicated, such as Historic Charleston Foundation). The goal is promote dissemination of information so that others working in the field will have access to comparative data. The Chicora data come primarily from either archaeological investigations that have resulted in the exposure of architectural ruins or through work on various cemetery projects.

Mortar Analysis

We have attempted to provide a concise description of the various samples in order to make the information more useful to others, including information on the date of the sample, the type of masonry, a brief interpretation, and the type of analysis. Interpretation, of course, can be problematic and we encourage others to make their own interpretation based on the data presented. Where type of analysis is listed, the primary two are either "simple acid digestion," meaning the technique presented by E. Blaine Cliver ("Tests for the Analysis of Mortar Samples," APT Bulletin, vol. 6, no. 1 (1974), pg. 68-73) or "gas collection" meaning the technique presented by H. Jedrzejewska ("Old Mortars in Poland: A New Method of Investigation," Studies in Conservation, vol. 5, no. 4 (1960), pg. 132-138). For a review of these techniques, and the issues surrounding mortar analysis, see Lorraine Schnabel, "Mortar Analysis," Building Renovation, Sept./Oct. 1993, pg. 25-28. The samples are listed below in chronological order of their analysis. In general the presence of either significant levels of soluble complex silicates or fines indicates that the mixes were slightly to moderately hydraulic. Those samples containing <10% solubles or fines are identified as non-hydraulic. Those samples with >10% and especially >20% are identified as moderately hydraulic and possibly natural cements.

Recently Lorraine Schnabel, in her article "Mortar Analysis Part 2: Analytical Methods" in the APT Bulletin, vol. 40, no. 2 (2009), questions the usefulness of either approach. Schnabel comments, "Advances in the field of mortar analysis have unequivocally demonstrated that the simple acid-digestion methods proposed by E. Blaine Cliver and H. Jedrzejewska are not suited to the general analysis of historic mortar. These methods are limited, in that they have no utility for mortars with acid-soluble aggregate, and Cliver's method is fundamentally flawed in the conclusions that can be drawn regarding original binder composition."

The bulk of this criticism is based on the study by John Stewart and James Moore, "Chemical Techniques of Historic Mortar Analysis," in Mortars, Cements, and Grouts Used in the Conservation of Historic Buildings (ICCROM, 1981), pg. 297-310. Stewart and Moore used the Cliver and Jedrzejewska methods to test a series of standard mortars of known composition. Cliver's method failed to correctly identify the composition of any of the test mortars. Jedrzejewska's method was more successful, but the technique is "temperamental in practice" making it difficult to obtain consistent, and replicable, results. In addition, it is of limited use when the mortar contains significant amounts of hydraulic material.

While Schnabel advocates the use of petrographic, XRD, and SEM studies, these are far more expensive and few clients are prepared to fund such studies. The results below should be interpreted and used with caution.

An article that may be interest is "Analyzing Mortars and Stuccos at the College of Charleston: A Comprehensive Approach." This article demonstrates how the use of petrographic and atomic absorption studies can provide a wealth of information not available from more simple wet chemistry techniques.

Bricks

The table below provides data on a small variety of brick samples identified primarily from archaeological or cemetery sites. As for the mortar analyses above, information is provided on the location, the approximate date, the type of brick, and any analysis that might have been conducted on the brick (regrettably little is available).

Conservation   |   Working in Cemeteries   |   Conservation Ethics   |   Cemetery Forms   |   Lawn Maintenance   |   Cleaning

Resetting   |   Cemetery Ironwork   |   Stucco and Whitewash   |   Disaster Planning   |   Mortar and Brick